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Commit b8865767 authored by Kim Phillips's avatar Kim Phillips Committed by Christoffer Dall
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ARM: KVM: user_mem_abort: support stage 2 MMIO page mapping 



A userspace process can map device MMIO memory via VFIO or /dev/mem,
e.g., for platform device passthrough support in QEMU.

During early development, we found the PAGE_S2 memory type being used
for MMIO mappings.  This patch corrects that by using the more strongly
ordered memory type for device MMIO mappings: PAGE_S2_DEVICE.

Signed-off-by: default avatarKim Phillips <kim.phillips@linaro.org>
Acked-by: default avatarChristoffer Dall <christoffer.dall@linaro.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent df6ce24f

arch/arm/kvm/mmu.c

+8 −3
Original line number Diff line number Diff line
@@ -759,6 +759,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
	struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;

	struct vm_area_struct *vma;

	pfn_t pfn;

	pgprot_t mem_type = PAGE_S2;



	write_fault = kvm_is_write_fault(kvm_vcpu_get_hsr(vcpu));

	if (fault_status == FSC_PERM && !write_fault) {
@@ -809,6 +810,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
	if (is_error_pfn(pfn))

		return -EFAULT;



	if (kvm_is_mmio_pfn(pfn))

		mem_type = PAGE_S2_DEVICE;



	spin_lock(&kvm->mmu_lock);

	if (mmu_notifier_retry(kvm, mmu_seq))

		goto out_unlock;
@@ -816,7 +820,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
		hugetlb = transparent_hugepage_adjust(&pfn, &fault_ipa);



	if (hugetlb) {

		pmd_t new_pmd = pfn_pmd(pfn, PAGE_S2);

		pmd_t new_pmd = pfn_pmd(pfn, mem_type);

		new_pmd = pmd_mkhuge(new_pmd);

		if (writable) {

			kvm_set_s2pmd_writable(&new_pmd);
@@ -825,13 +829,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
		coherent_cache_guest_page(vcpu, hva & PMD_MASK, PMD_SIZE);

		ret = stage2_set_pmd_huge(kvm, memcache, fault_ipa, &new_pmd);

	} else {

		pte_t new_pte = pfn_pte(pfn, PAGE_S2);

		pte_t new_pte = pfn_pte(pfn, mem_type);

		if (writable) {

			kvm_set_s2pte_writable(&new_pte);

			kvm_set_pfn_dirty(pfn);

		}

		coherent_cache_guest_page(vcpu, hva, PAGE_SIZE);

		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte, false);

		ret = stage2_set_pte(kvm, memcache, fault_ipa, &new_pte,

				     mem_type == PAGE_S2_DEVICE);

	}